The present invention relates to stator and rotor members for use in an apparatus for closing and/or regulating the discharge or tapping of molten metal from a metallurgical vessel. More particularly, the present invention relates to such members including a refractory or ceramic inner pipe-like element having therethrough at least one lateral opening and a refractory or ceramic outer pipe-like element having therethrough at least one lateral opening, one such element being stationary and forming the stator member, and the other element being rotatably movable relative thereto and forming the rotor member. The pipe-like elements are oriented preferably vertically. The elements have respective pipe-shaped portions through which extend the lateral openings and which also define radially confronting respective cylindrical inner and outer sealing surfaces defining a primary seal to prevent leakage of molten metal. The elements also have generally radially extending annular surfaces that confront each other and that extend annularly around the common longitudinal axis of the two pipe-like elements.
An apparatus of this general type is disclosed in German DE 35 40 202 C1 wherein an outer pipe is rotated with respect to an inner pipe to bring respective openings thereof into and out of alignment to open, close and regulate molten metal tapping or discharge. Cylindrical main sealing surfaces prevent the molten metal from escaping. Accordingly, the gap between the cylindrical sealing surfaces is dimensioned to be so narrow that the molten metal cannot pass therebetween.
Tests have shown however that, when pouring or discharge periods are relatively long, the gap between the main or primary sealing surfaces can expand. The result is that molten metal can pass therebetween when the apparatus is in the closed position, and this of course is very undesirable. A similar apparatus is disclosed in German DE 37 31 600 A1, but such known apparatus also suffers from the same problem.